1. Field of the Invention
The present invention relates to a fuel gas supply method for supplying a fuel gas to various types of fuel cells, of which a solid polymer electrolyte type fuel cell is one example.
2. Description of the Related Art
There has been developed a fuel cell (referred to as a solid polymer electrolyte type fuel cell) which is constructed by sandwiching fuel cells, each made up of a solid polymer electrolyte membrane having an anode side electrode and a cathode side electrode disposed on opposing sides thereof, between separators in a plural stacked fashion. Such fuel cells are being put to practical use in various technical applications. In addition, alkali type fuel cell, phosphoric acid type fuel cells, molten carbonate type fuel cells, direct methanol type fuel cells and high temperature solid oxide electrolyte fuel cells are also known.
In such types of fuel cells, by supplying a hydrogen gas (fuel gas) generated by steam reforming of methanol, for example, to the anode side electrode, together with supplying an oxidant gas (air) to a cathode side electrode, the hydrogen gas becomes ionized, and flows through the electrolyte, whereby an external electrical energy can be obtained from the fuel cell.
Incidentally, when generating hydrogen gas by steam reforming of methanol as described above, the methanol is not entirely steam reformed, but rather unreacted methanol can exist and be supplied to the anode electrode under a condition in which the hydrogen gas still contains such unreacted methanol therein. When this occurs, especially with a solid polymer electrolyte type fuel cell operating at low temperatures, a problem is indicated in that the starting voltage is greatly lowered due to the influence of such unreacted methanol.
Further, the above problem is not limited to cases in which the fuel gas is generated by steam reforming of methanol, but also occurs in cases where the fuel gas is generated by oxidation of methanol with air, or by reaction of methanol with steam and air.